Pokemon Diamond:Pokemon league or Victory road
Pokemon Emerald:Victory road or Calling Gym Leaders and Trainers
Pokemon SoulSilver/HeartGold:Pokemon league (Gym leaders if preparing for Red)
You can get the Leaders numbers only at Certain places, days, and times. They are listed below.
Elite 4
Just do the Pokemon League over and over
The elite four
in ever grand city
Unfortunately the only area for good training is the Pokemon league.
probably the bicycle route, or the victory road if you get there, or exp.share in the elite four
If you want a good place to level up your pokemon, I highly recommend the Iron Island or the Fuego Ironworks.
in the red shop or if you have a potion you should buy 300% potion
The best place to level up any Pokemon is the Pokemon league.By fighting the elite four at the Pokemon league your Pokemon will level up realy fast.If you have a low level Pokemon,give it an exp share and make a more powerfull Pokemon battle.
A good place train is the route next to Undella town. You can put exp. share on a weaker Pokemon let a stronger Pokemon do all the work and you will level up quickly because the Pokemon there are usually about level 50-60. Another way is by using the daycare to level up fast by just using your bike or running to level up.
Level up your best Pokemon to at least level 60.
The easiest way to level up is to feed Pokemon Rare candies.